"The Great Climate Flip-flop" is the cover story for the January 1998 issue of the Atlantic Monthly. If you're not fortunate enough to have your very own hard copy, you can find the full text in three different virtual places:

which will be out in Spring 2002
from the University of Chicago Press. It is already posted full-text
on the web and also in Palm
download format, for reading on the commute. It's about what
sudden climate flips did to human evolution over the last 2.5 million years.
It includes the climate history and flip mechanisms that I described in The
Atlantic Monthly cover story, "The Great
Climate Flip-flop" and covers the paleoanthropology as well.

ALTHOUGH William H. Calvin, the author of this month's cover
story, "The Great Climate Flip-flop," says that he is "not primarily an author,"
readers would be forgiven for assuming that he does nothing but write. A theoretical
neurophysiologist at the University of Washington at Seattle, Calvin has written nine
books, including five in the past seven years and two (How Brains Think and The
Cerebral Code) just last year. But he also maintains a punishingly busy schedule as a
researcher, investigating how brains work and evolve, and travels extensively on the
lecture circuit. Readers would therefore also be forgiven for wondering why Calvin
devotes so much of his precious time to following the study of climate change.
The answer, Calvin says, is that the evolution of the human mind is intimately linked
to abrupt climate change: our brains seem to have begun their transformation from
apelike to fully human just when temperatures on earth began their current trend of
jumping rapidly -- often within a single lifetime -- between warm and cold. Calvin
argues that in the context of brief environmental opportunities (periods of warmth)
and hazards (sudden icy temperatures), survival for our ancestors became dependent
on having highly agile, "jack-of-all-trades" minds. The flip-flop of climates, in other
words, led to the evolution of brains that could themselves flip-flop abruptly between
strategies for survival. In describing the minds that we have ended up with, Calvin is
fond of referring to a passage by William James that appeared in The Atlantic
Monthly in October, 1880. "Instead of thoughts of concrete things patiently
following one another," James wrote,

we have the most abrupt cross-cuts and transitions from one idea
to another, the most rarefied abstractions and discriminations, the
most unheardof combinations ... we seem suddenly introduced
into a seething caldron of ideas, where everything is fizzling and
bobbing about in a state of bewildering activity.

Creative thinking is now more important than ever. A central point in "The Great
Climate Flip-flop" is that the greenhouse gases we pump daily into the atmosphere
may well trigger an abrupt global cooling. But if we have helped to bring on such a
problem, we are also the only creatures on the planet with brains highly enough
evolved to solve it -- and solve it we must, even if, as Calvin points out, it won't
make our brains any larger. -THE EDITORS

William H. Calvin ("The Great Climate Flip-flop") is a theoretical
neurophysiologist at the University of Washington at Seattle.